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Takayuki Kubo
QUP Affiliate member
Assistant Professor
KEK, iCASA
e-mailkubotaka-at-post.kek.jp
I have extensive experience in theoretical and experimental research on superconducting resonator cavities for particle accelerators. My recent work has expanded into the theoretical exploration of applied superconductivity, utilizing techniques in superconductivity theory. This research encompasses a wide range of superconducting devices, such as particle accelerator cavities, kinetic inductance detectors, transition-edge sensors, superconducting diodes, and other related technologies.
Research Content
Recent work includes the theoretical study of kinetic inductance under bias current. Traditionally, this has been calculated using BCS or Ginzburg-Landau theories with phenomenological assumptions, such as the "slow (fast) experimental scenario," where the superfluid density oscillates with (or remains frozen under) the electromagnetic field. Using the Keldysh-Eilenberger formalism, I avoided these assumptions and showed that only the "slow experimental scenario" is valid. This stems from the fact that in electromagnetic response under bias current, the Higgs mode (oscillation of superfluid density) must contribute. My work provides the first framework for calculating kinetic inductance under bias current using only microscopic theory, applicable across various temperatures, frequencies, and impurity levels.
